Soft target takes tough blows for ADAS

| Environmental Testing

The GST can be assembled into a collapsible aluminium frame with foam and fabric coverings

Jonathan Newell finds out how test houses and proving grounds for autonomous vehicles and advanced safety systems now have access to a Guided Soft Target vehicle.

It’s hard to imagine a test plan for collision avoidance technology that doesn’t run the risk of a collision occurring. With a combination of expensive test and target vehicles, the costs for the development and testing of autonomous vehicles and Advanced Driver Assist Systems (ADAS) would rise to unacceptable levels.

For final safety ratings of consumer-ready vehicles, the world NCAP (New Car Assessment Programme) organisations like EuroNCAP and the USA’s National Highway Traffic Safety Administration (NHTSA) use a harmonised standard global vehicle target with a soft foam panelled body. This “Soft Car 360” is licensed for production in Europe by automotive test system supplier, AB Dynamics.

Next generation target vehicle

Now, AB Dynamics has launched its next-generation Guided Soft Target (GST) vehicle to fulfil the needs of the large development test houses. The GST has a new lower platform with a drive over height of just 100mm and can be used for both ADAS and Autonomous vehicle testing. Having such a low profile reduces the risk of damage to the test vehicle. Equipped with precise positioning, speed control and test vehicle synchronisation technology, the GST enables the test houses to generate repeatable, dependable results.

The construction of the GST consists of an aluminium Ultra Low-Profile Chassis (ULPC) with retractable wheels that recede in the event of being driven over, minimising shock input to the test vehicle’s suspension.

The aluminium frame is fitted with a foam panelled body, as used on the NCAP designated Soft Car 360, that can be reassembled in just 10 minutes following an impact. With some slight variation depending on the overall specifications, the entire vehicle can weigh as little as 315kg and can achieve 0.2g longitudinal acceleration with a foam body fitted and 0.8g maximum deceleration.

According to AB Dynamics’ business director for track test systems, Andrew Pick, the use of ADAS technology is becoming more widespread within the automotive industry and is seeing increasing levels of complexity as more and more autonomous functions are being developed. The move to full autonomy is characterised by the merging of increasing levels of sensor-based driver assist and collision avoidance systems.

“The ability to precisely test these capabilities in a repeatable environment is of vital importance so just as the technologies move forward, so too must the enabling test systems that are used for development. The new GST combines all the benefits of the previous generation platform with reduced risk of damage to the test vehicle,” explains Pick.

Synchronised Control

To be of full benefit to automotive test organisations, The Guided Soft Target can’t be just a passive object, but needs to have the ability to move, follow guidance paths and synchronise itself with other targets and with the test vehicle.

To this end, the latest generation GST is the result of collaborative development efforts between AB Dynamics and Dynamic Research Inc (DRI) and features AB Dynamics’ Path Following and Synchro control technology.

According to Pick, such collaborative work is an essential part of the company’s direction. “AB Dynamics is constantly looking for ways to develop its technologies to ensure that we remain at the forefront of vehicle testing and the preferred supplier to major vehicle manufacturers globally. The new GST is a vital tool for testing and proving emerging ADAS technologies, helping to accelerate their route to market,” he says.

For propulsion the Mk2 GST features a substantial 3.5kWh battery that is capable of sustaining a full day’s testing on a single charge, but if necessary can be quickly recharged or topped-up at the track-side via the inbuilt battery management system. Additionally, the lithium iron phosphate battery is formed from six identical packs that can be easily removed for safe shipping.

The battery provides the power to electric motors that can accelerate the GST to velocities in excess of 80km/h and all while being precisely controlled.

Positional control

Controlling the position of the target vehicle in relation to others that are in use as well as in relation to the test vehicle is achieved using AB Dynamics’ proprietary TrackFi radio.

TrackFi offers point-to-point data transfer using the standard 5GHz WLAN frequency, paired with specially designed, high-gain antennas. Data transfer bandwidth of 6 Mbit/s is possible at a range of 1km, making it suitable for sending real-time test data or even video.

TrackFi enables positional data to be shared with other AB Dynamics controllers via the Synchro interface, which allows its motion to be precisely synchronised with the test vehicle and other ADAS targets.

Pick explained that with its improved performance across a range of test-critical metrics and its advanced synchronisation capabilities, the Mk2 GST enables the safe testing of ADAS and autonomous systems in a broad range of scenarios, making it an ideal platform for ADAS targets.

“When it comes to vehicle testing, repeatability is key. Using Synchro, you can construct highly precise and repeatable events, which ensures that data is collected efficiently and effectively,” he says.

Testing with real vehicle targets is unthinkable given the risk of writing off a test car and the potential for injury.

“In contrast the electrically driven GST and Soft Car 360 provide a test tool that can be reused time and time again,” Pick concludes.

Long Distance Telemetry

The TrackFi telemetry system used on the GST was designed to enable reliable low latency data transfer over distances of 1km or more. Using standard licence free WiFi radio frequencies, TrackFi allows data to be transferred between moving vehicles or between a moving vehicle and a stationary base station, making it ideal for vehicle testing telematics at proving grounds.

ABD developed TrackFi to fulfil the requirements for reliable data transfer between a base station and one or more moving vehicles. Having tested existing telemetry systems, ABD identified a need to combine reliable data transfer over long distances with the use of licence free radio frequencies.

TrackFi uses the 5GHz wireless LAN (WLAN) frequency in accordance with IEEE 802.11n together with specially designed high gain antennas.

Configuration software is included which includes a survey function and a real time display of signal strength for each unit being used. The survey function allows the analysis of existing WLAN networks in operation at the proving ground, permitting the user to select the optimum frequency band to minimise interference.

TrackFi has a range of over 1km in a 360° horizontal plane with line of sight, assuming no interference is present. It uses a standard R145 Ethernet cable for data connectivity and is available with rubberised magnetic pads or vacuum mounts, so it can be used with different vehicle materials.

Jonathan Newell
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